Group D is transitional: the obverses have the Class V nose; the reverses are characteristic of Class IV, having the two leaves (or lash endings) descending from the rein curl, and lacking the emblem in front of the pony. The chronology is as follows:

Group D

Coins 12, 13, 14, 15.

The difference between the obverse of Coin 12 and the preceding coin is shown in the inset of Rybot's illustration: it appears that the end of the top whisk of the head is tucked in under the second curl. There is also an additional leaf to the curl of the whisk. It is unfortunate that Rybot did not illustrate the entirety of that particular coin, as it is not clear whether the other whisks are also similarly treated.

On the reverse of Coin 12, we see the change to the Class IV reverse design: the cross in front of the pony is omitted, and the rein curl is given two leaves that point downward. This feature remains unchanged for the rest of Series X. The driver's body is similar to that of Coin 11. The neck is omitted, and the connection of body and head is made differently: from a position just above the centre of the S-scroll of the driver's body, the line of his arm issues, and curves downward, connecting to his hand with a bead. From the shoulder position of this line, the diadem line rises, terminating at the third hair of the crest. The first and third hairs of the driver's crest extend downward to meet his nose. The driver's cheek section is concave at the top to accommodate the space of the eye. The driver's head is similar to that of the pony's, which originated on Coin 10.

There is a clear evolution in the design of the obverse of Coin 13: the ornaments in front of the head are arranged with more certainly here than in Coin 12. The beaded sections are replaced with solid lines, and the S-scroll in front of the nose is enlarged to be in better balance with the scroll above the nose. The nose itself slants outward slightly, and, interestingly, the leaf on the ornament in front of the nose parallels it here, just as it did on Coins 11 and 12, where the nose was vertical. The lips are reinforced by lines connecting the beads with the cheek section. The whisks were reconstructed as having only single leaves; they would, by necessity, be different from that of the previous coin, as there is no space for them to be tucked underneath any of the three front curls of the head.

The most important difference in the reverse of Coin 13 is the novel design of the sceptre head: here it is fleur-de-lis shaped, instead of the usual pellet within a beaded circle. The extra line at the front of the driver's face, seen in the previous coin, has been removed, thus simplifying the driver's head.

Coin 14 is represented by a single specimen. The die engraver, after perfecting the design in front of the head in Coin 13, suddenly abandons the entire concept, and begins experimenting, in this coin, with a scroll-like ornament that issues from the mouth. The lower part of this ornament is missing from the coin, but may be a simple curl. The upper part of the ornament consists of two lines that curve up and are joined with a bead to an outward facing curl. Rising diagonally from this curl, to a position in front of the whisk at the top of the nose, is a leaf.

All of the whisks on Coin 14 have the beaded sections seen on Coin 12, each whisk with a plain end curving around its adjacent hair curl, and just touching the end of the curl, as on Coin 12. Unlike Coin 12, each whisk on this coin has two leaves.

The reverse of Coin 14 is the same as that of Coin 12.

The obverse of Coin 15 has a mouth ornament consisting of two lines, one curving down from each lip, to meet in a curl turned outward in front of the neck. Both the curl itself, and a small section at the start of the upper line, are plain; the rest of the ornament is beaded. The nose on the obverse of Coin 15 foreshadows the Class IV style, with the nasal area represented by a line. Instead of the nose whisk, there is now a downward-pointing curl and leaf ornament engraved in a florid manner: the large leaf is engraved in a florid manner: the large leaf is engraved as an outline, and the curl behind it is reinforced with two additional curved lines.

The reverse of Coin 15 is similar to that of Coin 12; on another die there is the shoulder ridge, or extension of the pony's inner foreleg, as seen on Coin 13. Unless the shoulder ridge is of an unusual design I do not mention it in the catalogue. It seems to be an integral part of the design of Series X and Y. Its omission in some coins may only signify that the die engraver did not leave enough room to fit the shoulder ridge between the pony's chest and back sections.

Three of the four obverse dies of Group D have the reinforced stalked lips.

The last two coins of this group seem experimental. After perfecting the obverse design in Coin 13, the die engraver is unsure of what to do next. He reintroduces beads to some of the lines, tries different designs of the mouth ornament, and finally abandons the nose whisk in favor of a downward-pointing ornament. Why the die engraver should abandon a design, after apparently perfecting it, is discussed in Chapter Eight.